Art of coloring and fireproofing wood.



No Drawing.

5 UNITED STATES WILLIAM AUGUSTUS HALL, OF NEW YORK,

N. Y., ASSIGNOR T0 AMERICAN MAHOGANY COMPANY, A CORPORATION OF MAINE.

ART OF COLORING AND FIREPROOFING WOOD.

. Specification of Letters Patent.

Applicationfiled June 6, 1908. 1 Serial No. 437,078.

Patented June 14, 1910.

To all whom it may concern:

Be it known that I, WILLIAM A. HALL, a citizen of .the United States,residing at New York, in the county of New York and State of New York,have invented or discovered certain new and useful Improvements in theArt of Coloring and Fireproofing Wood, of which the following is aspecification.

This invention relates to the art of transforming wood by coloring andfireproofing the same, so as to produce, from the cheaper or more commonvarietiesof wood, such as birch, maple or gumwood, close fireproofedimitations of rarer or more expensive woods, such as black walnut,mahogany, etc.

The object of the invention is accomplished by a novel method oftreating the lnexpensive woods so as to render them fire proof and givethem the appearance and texture throughout their bodies of the morecostly woods.

' The invention is carried into effect by causing suitable coloring andfireproofing solutions to permeate the wood and to be diffusedthroughout its body so that when the wood is cut up, in making cabinetwork, or for other purposes, all parts of it will be suitably coloredand will be of a fireproof character, and there will be practically nouncolored, non-fireproofed streaks in the wood, but the coloring andfireproofing materials will be infused and diffused throughout the wood,but with considerably more of the coloring matter deposited in thesofter or more porous portions of the wood, such as the annual rings andopen grain vessels, thereby resulting in a very prominent development ofthe grain or figure of the wood.

The invention may be carried into effect either by what is known as thevacuum and pressure process, or by What may be referred to as the openvat treatment.

In practicing the invention by the vacuum and pressure processwell-dried lumber, in the shape of boards, planks, fiitches or deals, ofany convenient size, is subjected, in a closed receptacle, to a vacuumaction sufiiciently powerful and continued sufficiently long to removefrom the wood practically all the air therein contained, so as to makeit absorbent or receptive to the fluids to be applied later. It has beenfound preferable, during the vacuum process, to subject the wood to amoderate heat of say from 90 to "100 R, which has a tendency to open thepores of the wood. A combined coloring and fireproofing solution is thendrawn or pumped into the receptacle or chamber containing the wood untilthe wood is fully immersed in such solution. The coloring andfireproofing solution may be applied either hot or cold (preferably theformer) accord ing to its characteristics, and the solution will berapidly taken up by the absorbent Wood. When the receptacle is filledwith the solution, hydraulic or pneumatic pressure, preferably of say200 to 300 pounds or more to the square inch, is applied to the chamberof the receptacle and 1S maintained until the wood is impregnated by thecoloring and fireproofing solution to as great a degree as possible; thetime required for this varying from two to three hours to ten or twelvehours or more, according to the thickness or hardness of the lumberunder treatiient and the amount of pressure maintaine The coloringsolutions used may be of any character that have a sufiiciently highcapillary activity, but alkaline aqueous solutions of bark or woodextract, such as those pro duced from hemlock, spruce or mahogany, arepreferred, the coloring materials selected of course being those whichwill not be injured to any extent by temperatures of 212 F., orthereabout.

The fireproofing solutions which are to be mixed with the alkalinecoloring solutions, must be of such a character as not to precipitatethe coloring solutions, and the coloring solutions must be of such acharacteras not to injure or deteriorate the fireproofing solutions inany way, by reason of being antagonistic thereto. The fireproofingcomposition which I have found, by extended experiments, to be mostsatisfactory consists of a mixture of sulfate of ammonia and phosphateof soda. Sulfate of ammonia is a very strong fireproofing substancewhich not only mineralizes the fiber of the Wood, but, which whensubjected to heat, discharges ammonia gas which has a tendency toextinguish flame. Owing, however, to the acid character of this salt itis not suitable for use alone with alkaline coloring solutions, as ithas a tendency to precipitate such solutions, so that they can not bemade to permeate the wood as thoroughly as may be desired. Also thisacid salt cannot be used 110 alone as a fireproofing substance inconnection with alkaline coloring solutions, for the reason that thefireproofing qualities of the. substance are greatly impaired ordestroye I have discovered that by mixing a suitable proportion ofphosphate of soda, which is an alkaline fireproofing salt, with thesulfate of ammonia the acid of the latter is neutralized and the wholemixture is rendered neutral or slightly alkaline; and such fireproofingmixture will not precipitate or injure the alkaline coloring solutionsor substances with which it may be mixed, nor will the fireproofingqualities of the mixture be impaired by the alkaline solution. Vhilephosphate of soda is not, of itself, so strong a fireproofing substanceas sulfate of ammonia, I have found that a mixture of these two salts ismore strongly fireproofing than either when used alone, for the reasonthat the sulfate of ammonia is not, of itself, a very good mineralizingsalt, its fireproofing qualities being largely due to the evolution ofgases which do not support combustion; whereas the phosphate of soda isa very strong mineralizer, but is deficient in a capability of evolvingflame-extinguishing gases. While the invention is not to be understoodas being limited to any particular proportions of these fireproofingsalts in the mixture, it may be stated that experiments have determinedthat phosphate of soda may, and preferably will, form from onethird toone half of the mixture.

Instead of using sulfate of ammonia in the fireproofing mixture,phosphate of ammonia might be used with equally good effeet; but owingto the much greater cost of the latter salt the former will preferablybe employed. Also, instead of using phosphate of soda as an alkalinesubstance in the fireproofing mixture sulfid of soda might be employed;but the former salt is much preferred owing to its greater elliciency.Other fireproofing substances or solutions which, either alone or whencombined together will be of a neutral or alkaline character, or whichwill not be deteriorative of or injurious to the coloring solutions, mayalso be used in place of the preferred salts or substances abovementioned; and the invention or discovery is therefore not to beunderstood as being limited to any particular fireproofing substances solong as those employed form a composition which is of a neutral oralkaline character and which is harmonious with or non-antagonistic tothe alkaline coloring solutions.

Instead of effecting the coloring and fireproofing of the wood by thevacuum and pressure process above described, well-dried wood may beimmersed in a coloring and fireproofing solution, of the characterhereinbefore indicated, contained in an open vat by such alkalinesolutions. But

or receptacle, and in which it may be boiled for two or more days,tocause the coloring and fireproofing solutions to permeate the wood andto be properly diffused therein;

or, instead of being boiled in a combined coloring andfireproofingsolution the wood may first be boiled in the coloringsolution in an open vat and afterward plunged into a cold fireproofingsolution which, owing to contraction, will be caused to be absorbed byor struck into the wood; and this cold fireproofing solution mayafterward be heated, and by boiling the wood therein for some time thecoloring and fireproofing materials will be thoroughly dilfusedthroughout the wood.

It will be understood that wood which has been subjected to a coloringand tireproofing treatment by either of the methods above described willbe so transformed as to closely resemble the higher priced wood which itmay be desired to imitate, according to the character of the coloringsolutions which may be employed in this treatment; and such wood willalso be rendered fireproof. The treatment of the wood by either of themethods above described has atendency to harden and toughen the wood,and also serves greatly to develop the grain thereof, so that naturalwoods having but little grain figure will come out with a highlydeveloped and beautifully figured grain, and will therefore be verydesirable for any purpose where an ornamental fireproofed wood may beemployed. This result is largely due to pigment-like deposits of thecoloring matters in the grain cells, together with the fireproofingsalts, such deposits resulting from precipitation of the coloringmatters from the coloring solutions partly by dialyzation and partly bythe effect of the weak natural acids contained in the wood.

Having thus described 111 invention I claim and desire to secure byetters Patent:

1. The herein described fireproofed and artificially colored wood,having harmonious coloring and fireproofing materials distributed anddiffused together throughout the wood, and the grain of the wood highlydeveloped.

2. The herein described fireproofed and artificially colored wood,having an artificial coloring material and a mixture of acid andalkaline fireproofing salts distributed and diffused throughout thesame, and the grain of the wood highly developed.

3. The herein described fireproofed and artificially colored wood,having an artificial coloring material and a mixture of sulfate ofammonia and phosphate of soda distributed and diffused throughout thesame, and the grain of the wood highly de-' veloped.

4. The herein described process for colorcoloring and fireproofingmaterialsously, the coloring solution hein of an alkaline'character, andthe fireproo material consisting of a mixture of sulfate of ammonia andphosphate of soda.

In testimony whereof I aflix my signature, in presence of two witnesses.

WILLIAM AUGUSTUS HALL.

Witnesses:

JOHN CARRINGTOK YATES, WALTER M. SCHEUMAKER.

